1. Field of the Invention
The invention relates to highly viscous hydraulically-applied mulch media containing porous particles to enhance erosion control and vegetation establishment performance of the mulch matrix for application to soil and soil-like surfaces.
2. Background Art
The purpose of mulches is to increase seed germination and decrease soil erosion to allow seedlings to become firmly established in the soil. Mulches typically consist of natural materials such as straw, hay, wood, paper or compost. The mulches are generally mixed with water and placed in a holding tank where they are mixed and then sprayed onto the desired soil surface. Reference is made to the sprayable mulch of Hansford, U.S. Pat. No. 4,297,810 entitled “sprayable hydromulch”, which is comprised of hay, magazine paper stock, a binder and a coloring agent.
These chemically bonded natural fiber hydraulically-applied mulches may rely upon soil chemistry or positive-negative attraction modes to secure the soil surface for short term erosion control. Mechanically and/or chemically bonded fiber matrices rely upon physical, fiber to fiber and/or chemical bonding for erosion control performance. Although the mulches may be sufficiently well bonded, erosion control and plant establishment performance has been limited for a number of reasons. In some instances the chemically-bonded mulch forms an almost impenetrable layer over the soil surface that limits water and oxygen needed for plant growth. Additionally, the mulch layer itself can be difficult to penetrate by germinated seedlings. Mulch matrices which lack mechanically interlocking fibers have difficulty absorbing raindrop splash energy, are susceptible to sheet erosion and cannot withstand prolonged concentrated flow energy.
Crimped natural fibers or man-made fibers comprised of polyester, polypropylene, cellulose, and other natural and man-made polymers have been linked to form a matrix, which allows penetration by germinated seedlings and allow air, water and light to reach to the soil surface. However, these synthetic fibers are not readily biodegradable and the natural fibers, though biodegradable, do not retain the matrix formation required to handle high rates of concentrated flow energy associated with rilling erosion. Rill erosion is the removal of soil by concentrated water running through streamlets. This level of erosive energy is commonly associated with long slope length or areas of overland flow.